Bank and trunk cable multipling system



June 21,1927.

- 1,633,118 H. B. MGELYEA BANK AND TRUNK CABLE MULTIPLING SYSTEMOriginal Filed Dec. 18, 1922 '7 S'heet's-Sheet 1 um w km* June 21, 1927.1,633,118

H. B. MCELYEA BANK AND TRUNK CABLE MULTIPLING SYSTEM Original Filed Dec,18, 1922 '7 Sheets-Sheet 2 H E11-:leg E HQE IgE-E1 BANK TRUNK CABLEMULTIPLING SYSTEM H. ABL MOELYEA v rsheets-:sheet 5 Original Filed Dec.18, 1922 2;/

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June 21 1927.

H. B. MELYEA BANK AND TRUNK CABLE MULTIPLING SYSTEM s s I i @iw I 411@@l l H a I' @IH-Pl@ @@@i CEI@ I l: I @E originalilaa Dec. 18. 1922 '7Sheets-Sheet 6 June 21, 1927. 1,633,118

H. B. McELYEA BANK'AND TRUNK CABLE MULTIPLI'NG SYSTEM Original FiledDec. 18.- 1922 7 Sheets-Sheet 7 Harley B HEgea Z. M HUT Patented June2l, 1927.

s'ni'resA f 1,633,118 PATENT OFFICE.

HARLEY B. MCELYEA, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNEASSIGNMENTS,'

TO AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A CORPORATION F DELA-waan.

BANK AND-TRUNK CABLE MULTIPLING SYSTEM.

.Application led December 1.8, 1922, Serial No. 607,485. RenewedDecember 4, 1928.

The present invent-ion relates to bank and trunk cable-multiplingsystems in general, that is, systems for multipling to ethervthe bankcables of selector switches an the trunk 5 cables leading to theswitches in the next series in automatic telephone systems; and the mainobject is the production of an improved system' ofthe above named type,whereby the 'bank and trunk cables in an automatic telephone system maybe readily Inultipled together in any desired manner, and may be latermultipled together readily in any other manner as the necessity arises.Another object, incidental to the carrying out of the main object, isthe production of a new and improved distributing frame for use inconnection with the improved multipling system which may be manufacturedcheaply; which is simple and easy to install;-

and which permits the bank cables to be connected together in eitherlarge or small groups, or in any one of a large number of differentcombinations, with a minimum amount of labor.

It is common practice in automatic telephone exchanges employing step'bystep selector switches of the vertical and rotary type to place theswitches side by side in ,shelves or rows of ten or twenty switches 3Weach, and to multiple the bank contacts of adjacent switches together ingroups of ten, the banks being multipled so that corresponding contactsare wired togetherl throughout the ten switches of any one group. Aplurality of switches with their banks so multipled are known in the artas a .shelf. It is also common practice to multiple a trunk cable tocorresponding levels ina plurality of shelves of switches 40 in order tosecure the correct amount of traffic fol` the switches to which thetrunlt cable extends.

It is very evident that when the abovenamed practice is followed, somesort of connecting frame or terminal assembly must be provided if theInultipling wires are not to become a hopeless tangle. According to thepractice which has been commonly followed heretofore, two suitablyconstructed parallelogram shaped mounting frames are placed in anupright position about two feet or more apart and parallel to eachother. The switches are placed on these frames in five or six horizontalrows with one row 95 above another and with two shelves of ten switcheseach in each row. A connecting cable, or bank cable as it is called,-connects the banks of each shelfof switches'to the terminal assemblyframe which is placed 1n an upright position across one end of the spacebetween the mount-ing frames. The word bay is commonly used to mean agroup of shelves of switches collectively that are connected by theirbank cables wit-h a common terminal assembl frame.

On the terminal assemb y frame'the bank cables are connected to flatterminals which are secured in long strips of insulating ma.- teriallaid on the'horizontal supports of the terminal assembly frame. Themultipling together of adjacent shelves is taken care of by so-called upand down multiples. An up and down multiple, it ma be stated, comprisestwo flat terminal strlps, similar to the terminal strips to which thebank cables are connected, and a connecting cable.

When one shelf is to be multipled withanother shelf,` its terminals andone set of terminals of an up and down multiple are soldered together. The terminals of the other shelf are secured in like manner to theterminals of the other strip of the same up and down multiple, and alsoto still another multipling strip if a third shelf is to be included inthe multiple. This process is repeated until the desired number ofshelves are multipled together. vThe number of shelves, of course, thatare multipled together is determined by the traffic conditions and oftenvaries considerably' among the different levels.

The outlets for a shelf or for a group of multiply connected shelves areprovided by trunk cables which also are terminated on the supports inlat terminals. These terminals are bent into engagement with andsoldered to the terminals of the desired shelf or to the terminals ofone shelf of a multiply connected group of shelves. v

While the foregoing method of multipling together the shelves and ofproviding outlets for the traflic has been successfully used for anumber of years, .it has been found to be inflexible as regards trafficchanges which occurmore or less frequently, and also as regardsadditions which 'involve regrouping and rearranging. These facts andothers of varyin importance have presented themselves an have given riseto the development of a distributing frame te rethe upper part of theframe.

place the oldy terminal assembly frame. This distributing frame isexceedingly fieX- ible as regards traiiic changes and as regardsregrouping necessitated by additions which are likely to occur from timeto time.

When the new distributing frame is used, it occupies the same relativeposition as the old terminal assembly frame, and comprises essentiallybank cable terminal blocks which are arranged in horizontal strips andoccupy the greater part of the space on the frame, and trunk cableterminal blocks which also are arranged in horizontal strils and occupyAhe terminals in both the bank cable terminal blocks and the trunk cableterminal blocks are of the pin type.

The up and down multiplin or the multipling between adjacent she ves, istaken care of by bare jumper wire which extends vertically along thefront of the distributing frame, and which is soldered to corres ondingcontacts on the various blocks whic are to be multipled together.

The rear end of each bank cable terminal block pin has two notchesinstead of one. The bank cable wire is fastened to the pin at one notch,leaving the other notch free so that a jumper wire can be fastened tothe pin to connect the multipled group with an outgoing cable to whichaccess is gained through one of the trunk cable terminal blocks in theupper part of the frame.

Referring now to the drawings comprising Figs. l-lO, inclusive they showvarious views of the new distributing frame, and also serve to give anunderstanding of a few of the many ways in which the improveddistributing frame can be used.

Figure l is a View, drawn to a considerably reduced scale, showing amounting frame fully equipped with twelve Shelves of switches and alsoan edge view of the new distributing frame, which frame serves as adistributing frame for the switches shown, and also for an equal numberof switches similarly located on a mounting frame behind the one shownand parallel to it.

Figure 2 is a front view of the improved distributing frame and showsthe bank cable terminal blocks and the trunk cable terminal blocks inplace, the trunk cable terminal blocks being those in the upper section,and the bank cable terminal blocks being those in the lower section.

Figure `3 is drawn to a larger scale than Figs. 1 and 2, and is a Viewof the section of the distributing frame `which is separated from themajor part by the dotted line 3 3, Fig. 2.

Figure 4 is a rear view of the section I shown in Fig. 3 with one bankcable 3l and one trunk cable 55 shown in place.

Figure 5 is a view of the improved distributing frame and the rst tivevertical rows of switches on either side, as seen from the top, with theframe-work shown above the dotted line 5-5, Fig. l, removed in order togive a clearer view.

Figure 6 is a top view of a bank cable terminal block and is, forexample, one of the blocks shown in the strip 53, Fig. 3. This block isdrawn to actual dimensions.

Figure 7 is a view showing more clearly the construction of a singleterminal, such as one of the terminals in the block shown in Fig. 6.Figure 8 is a diagrammatic view of the improved distributing frame, andshows in one particular situation the number of shelves which aremultipled together on the variouslevels and are jumpered to the desiredtrunk cables.

Figure 9 is a diagram of a second distributing frame interconnected withthe first by tie cables.

Figure 10 is a detailed diagram and shows an alternative method ofconnecting up the fourth level of bank contacts at the distributingframe shown in Fig. 8.

While the improved distributing frame vmay be used in connection withany desired automatic switch, the switches shown in Figs. l and 5 areassumed to be of the type described in connection with and shown in Fig.62 of the illustrations in the second edition of Automatic Telephony, abook by Smith & Campbell, published by McGraw- Hill Book Company, Inc.,New York. A photograph of selectors covered and mounted as indicated inFigs. 1 and 5 is shown in Fig. 98 of the above mentioned book.

In view of the illustrations above referred to, it is consideredunnecessary to show the switches in any detail and, consequently, theyare indicated only generally. However, the shaft and wipers of switch20, Fig. l, and also of the switch in the lower left-hand corner of thesame figure, are indicated to give some slight idea of how the switcheslook.

Referring now particularly to Figs. l-7, inclusive, the construction ofthe improved distributing frame and its position as regards theassociated switches and switch banks will be explained. The frame onwhich the switches shown in Fig. l are mounted, comprises essentiallythree suitably braced uprights, and the interconnecting cross-bars onwhich the switches are hung. Of the three switch supporting uprights,only two, 46 and 47, are visible. The other one is directly behind theupright 45 and in line with the uprights 46 and 47, the uprights 45 and48 being located far enough forward to allow the front part of theswitches to come behind them so that doors may be provided if desired.The relative positions of the uprights may be readily ascertained uponreference to Fig. 5 which,

' Fig. 1 for example, l

as before stated, is a top view of the distributing frame and the firstivevertical rows of switches.

The distributing frame, seen most clearly in Fig. 2, comprisesessentially the uprights 48 and 49 and the strips of terminal blockswhich are secured between them.

The switch mounting frame shown in Fig. l, the one behind it, and thedistributingy frame are bound together at the top by the four strips ofheavy angle irons 41-44, inclusive.

Taking the top row of switches shown in the irst ten switches, 1l0,inclusive, comprise a shelf and their banks are accordingly multipledtogether and are connected with the distributing frame by the cable 31.

The banks of the shelf of switches comprising switches 11-20, inclusive,are connected with the distributing frame by the cable 32. The othershelves of switches below are similarlyconnected as is indicated by theother cables.

As shown,

- shelves in the top row of Fig. 1 lead to the irst two bank cablestrips 53 and 54, Fig. 2; the -two bank cable strips immediately ybeloware left for the cables coming in from the other side of thedistributing frame; and the next two shelves of switches from the top,Fig. 1, are associated with the n fifth and sixth bank cablestrips, etc.This arrangement, however, is merely arbitrary and may be deviated fromas desired. For example, the arrangement may be such that the two topshelves, Fig. 1, may be cabled to the first and third strips, leavingthe second and fourth strips for cables coming in from the other side ofthe distributing trame.

The four strips located at the top of the distributing frame, Fig. 2,lrepresent terminal blocks to which the trunk cables which form outletsfor the trac from the associated switches are connected. As shown,

- there are five blocks in each strip, making `called six-pin blocksinstead o the threepin blocks shown.

The conductors of the trunk cable are connected to the lower end of thetrunk block terminals as is indicated by the position of cable 55, Fig.4, and when.the cables .are

connected, each set of three terminals represents one three-conductortrunk.

Referringnow particularly to Figs. 3, 4. and 6, it will be noted thatthe terminal blocks of a bank cable strip are secured bethe bank cablesJfrom the two irons 48 and 49, as can be seen most clearj 1y in Fig. 4.

Although anyone of a number of dierent methods may e used in placing thepins in thebank cable terminal blocks, vsuch as using sectional .blocksand blocks with holes in them, etc., the preferred construction is thatthe bank cable terminal blocks are molded composition, such ashard-rubber for example, and that the blocks are molded around theterminals.

It will be noted, upon reference to Figs. 3 and 4, that the terminals ina'bank cable block are arran ed in' ten groups of three,

one terminal a ove the other. However, the terminals are so staggeredthat no one terminal is directly above any other terminal in the sameblock, but is directly above the corresponding terminal in the blockbelow. This permits any desired number of con tacts located in avertical line Ato be multipled together in a neat workmanlike mannerwith uninsulated wire. The front of each of the terminals, ,as is seenbest in Figs. 6 and 7, is grooved so as to allow the bare jumper wire tobe centered on the terminal without diiiculty, and also to facilitatethe soldering of the jumper wire to-/thejerminal A few of the barejumper wires are shown in place and soldered in Fig. 3.

Referring now particularly to Figs. 4, 6, and 7 it will be noted in Fig.4 that the conductors of the bank cable 31 are connected to theterminalsat the rear of the bank cable terminal blocks. As shown in Figs. 6 and 7two sets of notches are provided for each terminal. One setl of notchesis for the bank cable which is placed on first, and which is connectedto the notches nearer the block, and the other set of notches is for thejumpers which are run from certain of the bank cable blocks to thecorrect trunk cable block in the upper part of the distributing frame.The jumpers are passed up from underneath through the desired one of thefive holes in the spreading strip such as the spreading strip 61, whichis to be seen most clearly in Fig. 6. The ends of two jumpers 74 and 7 5are shown in Fig. 4. The remaining part of the jumpers cannot be shownin Fig. 4 for the reason that they pass back through jumper rings in amanner similar to the jumpers shown in Figs. 1 and 5.

It may be seen that when the new distributing frame is used, as manyshelves as debank cable sired may be grouped together by multipling thecorresponding terminals on the front of ythe distributing frame withbare Wire, and that the group thus formed can be connected to thedesired trunks by means of jumdpers. With this arrangement, the up andmultiple on the front of the distributing frame may be varied so as toinclude more or less shelves of switches .as the occasion demands, andthe jumpers which connect the groups of shelves to the trunk cables maybe changed accordingly at will.

Referring now particularly to" Fig. 8, which as before stated, is adiagrammatic view of the improved distributing frame, the associatedshelves of switches are indicated by the thin horizontal rectangles oneither side, which are lettered A to L, inclusive, and A' to L',inclusive. The heavy lines which are below the rectangles representingthe switches, represent the'banks of thev switches, and the lines whichconnect tne switch banks with the horizontal rows of short heavy lineslocated in the middle of the drawing represent the bank cables.

One short heavy line in any horizontal row to which abank cable connectsindicates one complete bank cable terminal block, and is connected bythe bank cable to one level of contacts in the associated shelf ofswitches. The bank cables, of course, are so fanned out and connected,that the first block in each strip is connected with the first level ofbank contacts and so on to the tenth block, which is connected with thetenth level of bank contacts as is indicated by numerals placed underthe vertical rows of blocks at the bottom of the drawing. The order inwhich the shelves of switches are connected to the strips of terminalsin Fig. 8, it may be stated, is the same as is indicated in Fig. 2 bythe letters A-L, inclusive, and A-L, inclusive, placed opposite theterminal strips. Regarding the trunk cable terminal blocks shown abovethe bank cable terminal blocks, it may be said that these blocks areconnected up by trunk cables to the switches in the proper groups insuch a manner that the group connected with the first vertical row ofblocks is group No. 1, and so on in order corresponding with the banklevels which are underneath. This arrangement, however, is purelyarbitrary and may be varied to suit the requirements of any particularinstallation. It will be noted that ten vertical rows of trunk cableterminal blocks are indicated, while only five vertical rows are shownin Fig. 2. The reason for this seeining discrepancy is that one shortheavy line in Fig. 8 indicates only half of. one complete block as shownin Fig. 2, because one block contains twenty sets of contacts which issuiiicient for two levels. Also, it will be noted that there are morehorizontal rows of .Short horizontal lines indicating trunk cableterminal blocks than there are strips of blocks indicated in Fig. 2.This is due to the fact that when as many blocks are needed as are shownequipped in Fig. 8, some of the blocks shown in Fig. 2 must be providedwith six terminals in a set instead of three, in which case that blockis indicated by twice the usual number of short heavy lines. Noattempt'l has been made to indicate which of the strips of blocks shownin Fig. 2 are equipped with six terminals in a set for the reason thatany strip may be so equipped without altering the scheme.

It will be noted that certain of the spaces in the section allotted tothe trunk cable terminal blocks are left blank. This is done becausethere are no cables at present on these blocks. However, the terminalsmay or may not be on the blocks at those places, depending upon whetheror not there is a likelihood that they will be needed in the future.

The two upper rows of heav short lines indicate the blocks to which tiecables are connected, so as to link the distributing frame shown in thisdrawing with the one shown in Fig. 9, for a purpose that will appearmore fully as the description prograsses.

For the purpose of this description, it will be arbitrarily assumed thatthe distributing frames shown in Figs. 8-10, inclusive, are servingsecond or thousands selectors in one oiiice of a multi-cnice system withan ultimate capacity the switches shown in Figs. 8 and 9 are required toselect any one of a plurality of groups of a thousand lines each. Itwill be assumed further that the traiiic differs considerably amongstthe various thousand line groups, and that the ninth. and tenth levelsare dead :for the reason that the correspondinggroups are left blank.

It will be assumed further that if the trailic were equally dividedamongst the eight working levels, seven shelves multipled together onthe form a group of the proper size and with the proper margin of safetyto furnish traffic on any one level for ten trunks. Since, however,according to a previous assumption, the load is not equally dividedamongst the eight working levels, the arrangement is varied so that wehave insome cases more than seven shelves multipled together on onelevel and less than seven multipled together on another level. Forexample, on the first and sixth levels, where the traliic is relativelylight as compared with the other levels, eight shelves can be multipliedtogether and jumpered to one trunk cable as is indicated by the bundlesof jumpers represented by the three lines bearing the referencecharacters 27 9-281, inclusive, which connect the three groups of eightshelves each of the first-level working 'levels would I of ten oilices.Accordingly,

cating the drawings, no lines have been run-v to represent the otherbundles of jumpers, but instead, the numbered circles have been providedto indicate corresponding points etween which the ten jumpers should berun. As an example, a bundle of ten jumpers should be run between twopoints indicated by the two circles numbered 113. j

It is assumed that the tratlic is comparatively lieavy on the fourth andfifth levels, which may be the case if the corresponding thousandsgroups handle a conslderable amount of private branch exchange traliicor contain a larger than usual proportion of business lines..Accordingly, only six shelves can be multipled together on these twolevels in order to furnish all the traic that can be safely carried byten trunks. Each of the other* four working levels, 2, 3, 7 and 8,carries the average amount of traflic and, accordingly, seven shelvesare multipled together on these levels. Since, there are twenty-fourvshelves associated with the distributing frame and, since twenty-four isnot a multiple `of seven, the shelves do not come out even, and therouping must be extended to the distri uting frame and associatedswitches shown in Fig. 9 by way of the series tie cable 272. Taking thesecond level, for example, three complete groups of seven shelves eachare formed on the distributing frame shown in Fig. 8 and the threebottom shelves are left over. The three bottom shelves are strappedtogether with the bare wire jumpers in the usual manner, and the tenjumpers are run to the proper trunk cable as is indicated by the twocircles numbered 104. Another set of ten jumpers is then run from one ofthe multiply connected' shelves in the partially formed group betweenthe points indicated kby the circles numbered 105. Since, four shelvesare required to complete the group, the first four shelves shown in Fig.9 are strapped together on the second level, and

the jumpers indicated by the circles num' bered 154 are run from thesecond block associated with the series tie cable 27.2 to one of thebank cable terminal blocks of the four multiply connected shelves,thereb completing the group of seven shelves whic is locatedv partly inone bay and partly in another bay.- As can be seen, each of the otherthree levels 3, 7, and 8 are taken care of in a similar manner. When thebottom of the distributing frame shown in Fig. 9 is reached, it is foundthat the shelves come out uneven again and, accordingly, the partiallycompleted group is carried over to the next bay, not shown, through theseries tie cable which extends to the next bay. This is carried outuntil the group comes out even, or until the last bay is reached and, if

a partially filled roup is encountered on the last bay, it may e takencare of by interconnecting it with one or two of the preceding groups orby any other Well-known expedient, such as reducing the number ofswitches to which is' has, access and making the remaining contactsartificially busy.

It is vthe usual practice, when one or more levels of a selector aredead, to multiple the contacts together throughout several bays .or insome instances throughout all the bays of selectors inthe oliice, and toconnect the group to an. operator 'by way of a few socalled dead leveltrunks. Accordingly, the ninth and tenth levels on the distributin frameshown in Figs. 8 and 9, are strapped together from the top to thebottom, and the two levels are multipled within each bay byfa set ofjumpers which are shown on the bank cable terminal blocks of the shelvesB and B2, respectively. It is assumed that the trunk cable with whichone of the circles 132, Fig. 8, is associated, is the one containing thedead level trunks and, consequently, the bundle of jumpers which is runbetween the points indicated by the two circles 132, provides an outletfor any calls which may land accidentally on the ninth and tenth levelsin this bay. These dead level trunks are multipled over to the remainingbays through the multiple tie cable which is connected to the top'set ofterminal blocks through the bundle of jumpers indicated by thecircles.133. The dead4 levels in the other bays are jumpered to thecorresponding blocks of the multiple tie cable and are thereby connectedwith the dead level trunks. For example, the ninth and tenth levels ofthebay shown in Fig. 9, are connected with the multiple tie cable by abundle of jumpers indicated by the' circles 185.

Referring now particularly to Fig. 10, which as before stated, is adetailed diagram showing an alternate method for combining severalshelves of switches so as to enable the outgoing trunks to handle thesame numberr of calls with fewer lost calls or a larger number of callswith the same percentage of 10st calls, this is a specificcross-connecting diagram and is shown merely to illustrate the amount offlexibility that can be secured with the improved distributing frameand, therefore, a specific case must needs be assumed. Accordingly, itwill be assumed that this diagram represents the fourth level of bankcontacts connected to the distributing frame shown in Fig. 8. In thisdrawing, one short heavy line indicates a set of three contacts, one

lhorizontal row of short heavy lines in the lower section indicates onebank cable terminal block, and one horizontal row of short heavy linesin the up er section represents a section of trunk ca le terminal blockto which ten trunks extending to a shelf of Switches in the next series1s connected. p

It is well-known that selector switches of the home position type suchas are assumed to be used in connection with the improved distributingframe, always seize the first trunk to which they have access if it isidle, and if it is busy, test the next one and so on, always taking thefirst idle trunk. That being the case, it is natural to expect that thefirst trunk will be in use more of the time than any one of the othersand that the trunks in order from 2 to 10 will each handle fewer callsthan the preceding one. This is what proves out in practice and is an`established fact. It is known also that if the trunks can be combinedinto groups of more than ten each, say twenty, the larger groups aremore eiiicient and, accordingly, the average number of calls handled pertrunk is greater.

Referring now again to Fig. 10, the trunks accessible from the level ofcontacts shown there are combined into two groups of twenty trunks eachinstead of four groups of ten trunks each as shown in Fig. 8, therebypermitting the two groups to handle the traffic with a better margin.The way in which the trunks are combined in the groups will now beexplained. The first five contacts of the shelves on this level f arestrapped together in six sets of four, and

the last five contacts are strapped together in two sets of twelve. Thismeans that any four shelves, the first four for example, have fivetrunks which are first to fifth choice to these four shelves, and whichare not accessible to any other switches, and that these four shelvestogether with two other groups of four shelves each have common accessas sixth to tenth choice to the five trunks which are multipled to thefirst twelve shelves an'd which are used only when all the' trunksindividual to a group of four shelves are in use.

This arrangement, so far, is the usual common and individual trunkingscheme. However, with the type of distributing frame commonly usedheretofore, it has been impractical to divide the traffic 'on theoutgoing trunk cables so that the various shelves of switches in thesucceeding series all carry practicall the same amount of traffic. Forexample, if one shelf of switchesin the succeedin train handles' thetraiiic from live indivi ual trunks and five common trunksv while-another shelf of switches handles traffic from ten individual trunks,the traic on the second mentioned shelf of switches will be very muchgreater than the traffic on the first shelf, and it will, consequently,be very difficult to figure out the correct'way to multiple the variousshelves together of the succeeding series of switches in order to loadthe cablesoutgoing therefrom propcontact sets of the firstfour shelves;thatl it carries the traiiic from the sixth, seventh, and ninth contactsetsv of the rst twelver shelves; and that it carries the traiiic fromlthe third and fifth contact sets of the second four shelves. These teitrunks according to a careful calculation, upon which it is unnecessaryto dwell here, carry approximately halfthe traffic on the group oftwenty and, consequently, the trafric carried by the cable which isconnected to the next trunk cable terminal block above will carryapproximately the same traffic for the reason that it takes care of theten remaining trunks of the group.

The remaining shelves in this bay are similarly strapped and jumpered onthe level in question, so as to form a second group of twenty-trunks,the jumpers being omitted in order to avoid complicating the dra-wings.4The places to which the jumpers are connected are indicated by thecircles which are numbered in pairs from 201 to 220, inclusive.

In order to even up the traffic amongst the various trunks in each groupof five `individual trunks, the first five trunks in each alternateshelf of switches, beginning with the B shelf, are reversed as may beseen upon 'referrin to the numerals applied to the contacts. or exam le,the first set of contacts on the distributin frame which is connectedwith the B she f is connectedW frame, that is, the sixth trunk is sixthIchoice, the seventh trunk seventh choice to all the switches, etc. Ifdesired, however, the sixth to the ninth trunks, inclusive, may bereversed in each alternate shelf in case the situation demands it.

The tenth trunk under normal conditions handles very little traffic,-being used only when five trunks in some individual oup are busy andwhen the four preceding com-l mon trunks are busy. Under thearrangeyment contemplated, the tenth trunk is last choice to all theswitches, so that a meter may be associated with the tenth trunk andwill indicate quite accurately whether or not the group of twenty trunksis properly loaded. For example, if'the meter associated with the tenthtrunk shows a very small number of calls or none at all for a giventime, theA indication is that the group of twenty trunks is loaded vtoolightly. On the other hand, if the meter indicates that the tenth trunkhandles a large number of calls in a given time, the group may beoverloaded to such an extent that a great many calls are lost for thewant of a suflicient number of trunks.

Regarding the multiple tie cable shown in Figs. 8 and 9, it may be saidthat this cable is used principally inmaking changes in the amount oftraiiie supplied to the various trunk cables after an exchange isinstalled and is seldom used to any great extent initially. As shown,this cable takes.

care of the dead level multiples between the bays shown in Figs. 8 and9, and the other bays in the same group, as is indicated by the bundlesof jumpers which are assumed to be run between the circles numbered133-and 185.

According to a foregoing assumption, the selector switches associatedwith the distributing frames indicated in Figs. 8 and 9 are thousandsselectors in a multi-office system and, accordingly, certain ones ofthese selectors are reached by office selectors in the local olicc,while the others are reached by way of the oice selectors in the otheroices of the system. It commonly occurs that the thousands selectorsreached by way of oney oiice has a tralic distribution amongst the4.various levels dierent than the traffic distribution of the thousandsselectors of the other ofices. This diference may be ,known incorrectlyor not at all before the installation is made and may become knownquantitatively-only after a traiiic study is made with the system inactual operation. It also often happens that while a study reveals thatone oice oiers` a traiiicon one level that is heavier than wasanticipated, another oice whose selectors are located on another bay hasa traic on the same level which is correspondingly.lighter than wasanticipated. When this condition arises, it is merely necessary toadjust the traiic on the level in question between the selectors ofthese two otlices only. In case the switches ot t-he'se two offices arelocated on adjacent bays, the re-distribution of traic is ordinarilyeffected through the series tie cables or the tie cables such as theseries tie cable 272, Figs. 8 and 9, which extend only between adjacentbays. If the switches in question, however, are located on bays whichare not adjacent to each other, the redistribution is made throughthemultiple tie cable such as tie cable 271, Figs. 8 and 9,

which is multipled through all the bayst terminals mounted'in saidstrips and pro-l trudlng outward therefrom on the front and rearthereof, certain of said terminals beingr multipled together throughouta plurality of said strips by conductors which extend along the front ofsaid frame, other terminals mounted on said frame, outgoing conductorssecured to said other terminals, and jumpers connected between therearof said multiply connected terminals to certain ones of said otherterminals.

2. A distributing frame having substantially parallel terminal stripsmounted thereon, terminals in said strips and extending outward from thefront and rear thereot, certain ones of said terminals being strappedtogether in rows substantially at right angles to said strips byconductors secured to 'said terminals on the front of said strips, twopoints of access on each terminal at the rear of the strip in which itis fastened, incoming conductors connected to each of said termlnals atone of said points of access, and outgoing jumpers connected to certainof said terminals in each multiply connected row, each of said jumpersbeing connected to the other of said two points otl access.

3.A A bay of switches, a distributing frame therefor, the shelves ofswitches in said bay being connected in groups on said frame as regardsone level of bank contacts, trunk cables terminating on said frame, andjumpers connecting said groups with said trunk cables.

4. A plurality of bays of switches, a distributing frame for each bay,and series and multiple tie cables extending between said bays tocombine them intoa single unit.

5. A distributing frame having sets of contacts arranged 1n vertical andhorizontal rows, agroup of normal position automatic selector switchesasociated with each horizontal row, certain of said contact sets in onehorizontal row being multipled with contact sets in one or more otherhorizontal rows, the banks of the switches in, each of Said groups beingmultipled together straight, and a cable connecting one switch bank ineach group to its associated horizontal row of contact sets, certainconductors in certain of said cables transposed as regards theirconnection with the contact sets terminals of another class arranged ina group apart from the terminals of the first class, straight bare wiresrunning vertically yes up the front of the frame, one wire for eachvertical row of terminals, said Wires serving to multiple together theseveral hor-izontal rows of terminals of the irst class, and jumperwires on the rear of said frame connecting the terminals of one of saidhorizontal rows with the group of terminals of the second class.

8. A distributing frame comprising two Vertical supports spaced apart, aseries of insulating strips extending horizontally between' saidsupports and secured thereto, a

plurality of pin terminals extending hori' zontally through each of saidstrips from front to rear, each pin including a front portion t'o whicha multiple wire may be soldered and a rear portion notched in two placesfor the attachment of a bank wire and a jumper wire, a second series ofinsulating strips extending across said supports, each strip having twoseries of perforations, terminal blocks mounted on the front of thestrips of said second series, and a row of vertical pin terminalsextending through each block with their ends in alignment with theperforations in two of said series.

9. An automatic switchboard section comprising a rack of switches and adistributing frame, said rack having a plurality of shelves of switches,bank terminals on said frame arranged in roups, groups of trunkterminals on said rame, cables extending from said shelves of switchesto said groups of bank terminals, trunk cables connected to said groupsof trunk terminals, sets of conductors connecting the groups of bankterminals to form major groups of bank terminals, and jumpers connectingeach major group of Abank terminals witha group of trunk terminals.

10. An automatic switchboard section comrising two parallel racks ofswitches and a 'stributing frame, each rack having a plurality ofshelves of switches, groups of bank terminals on said frame, groups oftrunk terminals on said frame, cables extending from the shelves ofswitches on one rack to one end of said frame and terminating on the oddnumbered roups of bank terminals, other cables exten ing from theshelves of switches on the other rack to the other end of said frame andterminating on the even numbered groups of bank terminals, trunk cablesconnected to said groups of trunk terminals, sets of conductorsconnecting groups of bank terminals to form major groups of.

bank terminals, certain major groups each comprising both odd and evennumbered groups, and jumpers connecting each major group of bankterminals with a group of trunk terminals.

l1. An automatic switchboard section comprising two parallel racks, eachhaving a plurality of superimposed shelves of switches, a distributingframe spaced away from said racks at one end and extending at 'rightangles thereto, the opposite ends of said frame being substantially inali nment with said two racks, respectively, an a rectangular frameworkat the top holding said racks andframe in position.

' 12. In an automatic switchboard section, an upright panel shapeddistributing frame, two parallel switch racks extending at right anglesto said frame and spaced apart a distance approximately equal to thewidth of said frame, means connecting said racks and frame together atthe top, switchl bank cable terminaison one portion of said frame, trunkcable terminals on another portion of said frame, and jumpers connectingcertain of said bank cable terminals with certain of said trunk cableterminals.

13. In an automatic switchboard section, an upright panel shapeddistributing frame, two parallel switch racks-extending at right anglesto said frame and spaced apart a distance approximately equal to thewidth of said frame, means connecting said racks and frame together atthe top, switch bank cable terminals on one portion of said frame, trunkcable terminals on another portion of said frame, jumpers connectingcertain of said bank cable terminals with certain of said trunk cableterminals, and a vertical row of jumper rings on each rack for holdl ingthe 'jumpers in orderly groups away from the back of said frame.

14. In an automatic switchboard section, a distributing frame, twoarallel switch racks adjacent thereto exten ing at right angles to saidframe and spaced apart a distance approximately equal to the width ofsaid frame, switch bank cable terminals on one portion of said frame,bank cables extending from said racks to said terminals, trunk cableterminals on another portion of said frame, and jumpers connectingcertain of said bank cable terminals with certain of said trunk cableterminals.

15.` In an automatic switchboard section, a

thereto extending at right angles to said frame, switch bankcableterminals on one ortion of said frame, bank cables extendlng fromsaid rack to said terminals, trunk cable terminals on another portion ofsaid frame, and jumpers connecting certain of said bank cable terminalswith certain of said trunk cable terminals.

16. In-an automatic switchboard section, two switch racks spaced apart,a distributing frame adjoining said racks, switch bank cable terminalson one portion of the frame, bank cables extending from said racks tosaid terminals, trunk cable terminals on another portion of said frame,and jumpers connecting certain of said bank cable terminals with certainof said trunk cable terminals.

17. In an automatic lswitchboard section, a distributing frame, a switchrack, switch bank cable terminals on one portion of-said trame, bankcables extending from said rack to said terminals, trunk cable terminalson another portion of said frame, and jumpers connecting certainA ofsaid bank cable terminals with certain of said trunk cable terminals.

18. In an automatic switchboard section, a distributing frame, twoparallel switch racks extending at right angles to said frame and spacedapart a distance approximately equal to the width of said frame, switchbank cable terminals on one portion of said frame, trunk cableterminals'on another portion of said frame, jumpers connecting certainof said bank cable terminals with certain of said trunk cable terminals,and` jumper rings on each'rack for holding the jumpers in orderly groupsaway from said frame.

19. In an automatic switchboard section, a distributing frame, twoparallel switch racks extending at ri ht angles to said frame, switchbank cab e terminals on one portion of said frame, cables extendin fromsaid terminals to said racks, trunk cab e terminals on another portionof said frame, jumpers connecting certain ofsaid bank cable terminalswith certain. of said trunk cable terminals,'and a row of jumper ringsfor holding the jumpers in Aorderly groups away from said frame.

20. In an automaticy switchboard section, a distributing frame', aswitch rack extend ing at right angles to said frame, switch bank cableterminals on one portion of said frame, cables extending from saidterminals to said rack, trunk cable terminals on another portion of saidframe, jumpers connecting certain of said bank cable, terminals withcertain of 'said trunk cable terminals, and jumper rings for holding thejumpers in orderly groups away `from said frame.

21. In an automatic switchboard section,v

a distributing frame, two switch racks, switch bank cable terminals onone portion connections between the frame and the racks. 23. Aconnecting frame comprising a plurality of parallel rows of spacedcontacts each contact' extending from the front to the rear of theframe, the corresponding contacts of all of the rows being in alignment,a plurality of multi-conductor cables mounted on one side of the frameeach adjacent one of said rows of contacts, thecorresponding conductorsof each of the cables .being connected to corresponding contacts `1n theadjacent row and conductors on the frame connecting correother side ofthe sponding contacts of certain of the rows.A

24. A connecting frame comprising a plurality of groups of spacedparallel rows of switchboard section osite ends A of which are adjacentboth of sai racks, and

contacts, the contacts of each row being stagu gered with respect to thecontacts in other rows of the same group-and in alignment withthecontacts of corresponding rows of other groups, a plurality ofmulti-conductor cables mounted on one side of the frame each adjacentone of the groups of contacts, the corresponding conductors of each ofthe cables being connected to corresponding contacts in the adjacentgroup, and conductors connecting corresponding contacts of bertain ofthe groups. j

2.5. In a telephone system, a plurality of rows of automatic switches,each switch containing a plurality of rows of contacts, a plurality oftrunks, means for connecting corresponding contacts of different rows ofswitches in multiple to desired trunks, said means comprising adistributing frame having aligned rows of contacts extending fromj thefront to the rear thereof, said trunks fbeing grouped in cables on oneside of the frame, conductors grouped in 'cables on the same side of theframe connecting the last mentioned contacts with the switch contacts,conductors on the other side of the frame connecting aligned contacts ofcertain adjacent rows, and jumpers connecting each of said lastmentioned conductors with a trunk.

In witness whereof, I hereunto subscribe my name this. 15th dayofDecember, A. D` 1922.

I HARLEY B. MOELYEA.

